US startups are developing proprietary technologies based on hydraulic fracturing to drill wells and store renewable energy from solar and wind in underground pressurized water reservoirs.
As the share of renewable energy in electricity generation in the U.S.’s largest oil state, Texas, grows, so does the need for energy storage to ensure clean energy is available when needed.
The new pressure storage technology could represent an alternative to lithium-ion batteries if it proves to be commercially viable and cost-effective in the new pressure energy storage systems.
In California and Texas, for example, grid-connected batteries now play an important role in stabilizing the system, wrote Ed Crooks, vice president of the Americas at Wood Mackenzie, earlier this year.
Currently, at least three Houston-based startups are working on pilot projects that involve storing water under pressure in underground reservoirs and releasing it on demand to drive a turbine and generate electricity.
“Carbon-free energy storage based on oil and gas technology is here because we can store renewable solar and wind energy underground,” said Mike Eros, chief geoscientist at Sage Geosystems, earlier this year when the company, founded in 2020, announced the first close of a $17 million Series A funding round for a commercial facility led by Chesapeake Energy.
The 3 MW facility, called EarthStore, will use Sage Geosystems’ technology that harvests energy from pressurized water stored deep underground. The facility will be able to store energy for short and long periods of time and can be combined with intermittent renewable energy sources such as wind and solar to provide baseload, on-demand power and inertia to the grid.
Last year, the company successfully demonstrated the EarthStore system in a large-scale commercial pilot in Texas. The pilot produced 200 kW for more than 18 hours (long-duration) and 1 MW for 30 minutes (load following), using Pelton turbines to generate electricity to run on-site equipment. The system has an efficiency of 70-75% and water losses of less than 2%, Sage Geosystems said in February.
Earlier this month, the company announced the project’s location after entering into a land use agreement with San Miguel Electric Cooperative Inc. (SMECI) for the Geopressured Geothermal System energy storage facility. The EarthStore system will be located in Christine, Texas, near SMECI’s lignite-fired power plant. Sage will act as a trader, buying and selling power to the ERCOT grid.
“Geothermal energy storage is a viable solution for long-term storage and an alternative to short-life lithium-ion batteries,” said Cindy Taff, CEO of Sage Geosystems.
Sage will also use its proprietary Geopressured Geothermal System to supply Meta’s data centers with carbon-free electricity, the company announced this week.
Other companies pioneering pressure storage systems include Fervo Energy and Quidnet Energy.
Fervo Energy boasts of having developed a proprietary geothermal technology called FervoFlex that enables reservoir energy storage and on-demand generation. Fervo’s horizontal well design connects underground wells to a series of hydraulically conductive fractures surrounded by impermeable rock. The company says its technology “effectively enables Fervo to operate its facilities to achieve multi-day energy storage characteristics in addition to the traditional benefits of clean, reliable geothermal energy.”
Fervo Energy is also backed by a US shale oil company. Last year, the company announced a $10 million strategic investment from Devon Energy.
Fervo said at the time that it was the first geothermal company to successfully drill and complete a pair of horizontal wells for commercial geothermal production, using technologies, capabilities and processes developed by Devon for oil and gas production.
Quidnet Energy, on the other hand, wants to develop a modified pumped storage system that stores energy underground using high-pressure water. To recharge, the team will pump water into trapped rock underground, creating high pressure.
Quidnet Energy calls the technology “geomechanical pumped storage” and says it can be deployed on a large scale and at very low cost.
“Underground rock layers are being converted into energy storage to enable large-scale integration of renewable energy and grid control,” the company explains.
The fracking process is less complex with these technologies than with oil and gas production.
Mike Eros, Sage’s chief geoscientist, told Inside Climate News that the company’s fracking process is about a tenth of the scale and intensity.
“We call it an earth battery,” he added.
By Tsvetana Paraskova for Oilprice.com
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